CROSS-CONNECTING
MMTTY with DX4WIN - by K8UT v4 (
The
following document describes the steps required to interconnect the DX4WIN
logging program to the MMTTY RTTY program inside one computer, so that DW4WIN
now has a full-featured RTTY program lashed onto it. All program control is
through DX4WIN, so all you have to do is start MMTTY and run it in
"headless" mode. This means that the RTTY scope and waterfall come
from MMTTY, but RTTY text display, logging and keyboard macros all work through
DX4WIN, giving you the ability to use DX4WIN's %keys for callsign, signal
report, name, etc.
Cross-connecting MMTTY and DX4WIN requires a sound card and at least one serial port, depending on whether you interconnect the two software programs using software interconnect of hardware interconnect.
HARDWARE INTERCONNECT: This method requires three serial ports. Two of the serial ports are used with a null modem cable to allow DX4WIM to communicate with MMTTY. All you need from the third serial card is DTR/RTS - which is how MMTTY keys the rig into transmit/receive mode. (I also have a keyed line from my LPT port - I use this to key the transmitter in CW and PSK modes from within DX4WIN)
SOFTWARE INTERCONNECT: This method only requires one serial port, from which you connect the DTR/RTS line to key the rig into transmit/receive mode. Rather than install two hardware serial lines for the interconnect, you install a free software program to emulate the two lines. You can download the program from http://www.mixw.net/related.htm . Unfortunately, the program only works on Windows 2000 and XP, so if you are still on Windows 9x or ME, you must use the hardware interconnect described above.
Both the
hardware and the software interconnects have been demonstrated to run on a
homebrew 866 MHz Pentium III PC. Since running these two programs
simultaneously requires some significant processing power (graphics, I/O, sound
card, timed interrupts) slower PCs may be incapable of keeping up with the
real-time processing demands of RTTY signals.
I created new DX4WIN keyboard macros to talk to the TNC
emulator in MMTTY. I have another document that describes my DX4WIN keyboard
macros.
-larry
K8UT
VERSION
INFORMATION:
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DX4WIN
5.02, and MMTTY 1.62
HARDWARE
ARRANGEMENTS:
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To keep
my explanation simple, I will refer to COM1 as the MMTTY keyed line to the rig,
COM2 as the MMTTY RTTY serial line, and COM3 as the DX4WIN RTTY serial line. If
you are a DX4WIN user, you probably have another connection for CW or PSK
keying your rig from DX4WIN - that connection has no bearing on this
configuration (I happen to use the LPT port method).
COM1:
Build a DTR/RTS interface cable (using the single transistor circuit in the
documentation of either DX4WIN or MMTTY) that will connect your computer's COM1
port to your rig's MIC PPT plug or an ACC socket. This cable will shift your
rig to transmit/receive based on signals from MMTTY (remember, MMTTY is the
back-end part of this equation)
COM2 and
COM3: Build or buy a "null modem" cable. (there are many references
on the Internet for building such a cable, depending on whether your serial
ports are 9 pin or 25 pin) Plug one end into your COM2 port, the other into
your COM3 port. This cable is the mechanism whereby DX4WIN and MMTTY send
information to each other.
SOUND
CARD IN/OUT:
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Connect
the "line out" or "speaker out" from your sound card to
"mic in" on your rig; and the "mic in" on your sound card
to "audio out" on your rig. This connection is well documented in
both the DX4WIN and MMTTY references. Some folks think you need transformers
and dropping resistors for impedance matching. I use a straight connection between
the rig and computer, and adjust the audio levels with the Windows volume
controls. You will have to do some experimenting to get this the way you like
it. If you are already running PSK from DX4WIN, you are all set. If you are NOT
already running PSK, you'll be able to after you get this running. HOWEVER,
keep in mind that it is MMTTY, not DX4WIN, that "talks" to the sound
card for RTTY. MMTTY is the back-end of this mode.
NOTE:
There are many interface "kits" and products that range from $25 -
$150 that will connect your keyed lines and sound cards. Although I built my
original interface from Radio Shack parts, it was a pain. Later, when I decided
that I wanted to run multiple modes, and RTTY FSK, and clean up the mess of
wires behind the bench, I decided to purchase one of the more expensive
commercial interfaces.
DX4WIN
SETTINGS:
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You must
configure DX4WIN to talk to the COM3 port, and the com settings must match
those of COM2 that MMTTY cross-connects. These settings are found in DX4WIN's
<F>ile, <P>references, RTTY.
RTTY
interface:
Type : regular
Baud rate: 4800
Flow control: RTS/CTS
Data/Parity: 8 bits/no parity
Scrollback
capacity: 500
Options:
X check for Dxspots
_
announce DX to other window
X
Always in immediate mode (IMPORTANT!)
X Use bell character'
X
Show function keys
MMTTY
SETTINGS:
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You must
configure MMTTY to talk to the COM2 port, and the comm settings must match
those of COM3 that DX4WIN cross-connects. These settings are found under
MMTTY's <O>ptions tab. There are lots of settings on these tabs - I will
only talk about the ones that I changed, or that make a difference in setup.
<O>Ptions,
<S>etup
PTT: COM1
<O>Ptions,
<S>etup MMTTY, Misc
Sound
Card Buff: 512 (IMPORTANT - setting this higher REALLY bogged down my computer)
For AFSK operation: Tx Port: Sound
For FSK operation: COM-TxD
<O>Ptions,
<S>etup TNC Emulation(T)
Port definition
Port:
COM2
Baud:
4800
Data
length: 8 bits
Stop: 1
bit
Parity:
None
Flow
control: CTS
TNC type: TNC241
Local echo: After Sending
X
Disable window (IMPORTANT - see text)
_
Stay on top
OPERATING:
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For AFSK
transmission, your rig must be in lower sideband mode. For FSK operation, you
will need an FSK keying line to your rig, and the rig must be in RTTY mode.
Start
DX4WIN first, then launch MMTTY. If you have the two serial ports configured
properly, MMTTY will send a copyright notice and "Receive/Transmit"
instructions to DX4WIN's RTTY window. You must go to the DX4WIN RTTY send
window and press the <ctrl>R key to begin receiving RTTY text.
See my
other document on function keys and macros.
To go to
transmit mode, press <ctrl>T. To return to receive mode, type
<ctrl>R or a "\".
LESSONS
LEARNED:
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1. The
DX4WIN PSK window cannot be open when running MMTTY, because the two programs
will fight for control of the sound card in your computer. When switching from
RTTY to PSK, you must first shut down MMTTY before opening the DX4WIN PSK
window.
2. DX4WIN
RTTY settings MUST be in "always in immediate mode" for the macros to
work properly
3. The
MMTTY "Disable window" setting will minimize the screen space
required by MMTTY, yet still allow you to see the tuning window. It also eliminates
the confusion created when seeing two sets of receive and transmit text (one
set from MMTTY, one set from DX4WIN). HOWEVER, during testing and debugging it
is very helpful to see what text is flowing back & forth between MMTTY and
DX4WIN - so you may want to leave this setting unchecked until you get the
programs working properly.
4. In
transmit mode, DX4WIN has a very limited transmit buffer with no
<backspace> or <delete> key. So if you make any errors while typing
you must either: send the mis-typed characters and hope the other operator can
understand you; send XX to indicate an erasure and then re-type the text; or
Press the <ctrl-R> key to shift to Receive mode (which empties the
transmit buffer) then press <ctrl-T> to resume transmitting. None of
these alternatives are very attractive, IMHO – which is why I operate MMTTY in
stand-alone mode for everyday rag-chewing, and only use MMTTY/DX4WIN in
cross-connect mode for contests.